1. Field of the Invention
The present invention relates to a tube-enlarging press for fixing the fins and tubes of a cross fin/tube type heat exchanger and, more particularly, to a tube-enlarging press which makes it possible to automatize the arrangements and preparations for jigs involved which are required to be performed in conformity with a change in the specifications of the heat exchangers.
2. Description of the Prior Art
The fixing of the fins and tubes used in a cross fin/tube type heat exchanger is performed by way of tube enlargement. Since, however, these elemental members are made of thin materials, at the time of tube enlargement the fins and tubes are liable to be buckling or bent. For the purpose of preventing such buckling, it is necessary to support the entire surfaces of those elemental members, for example, by supporting the fins at the outer peripheral portions thereof and the bend portions of the tubes along their bends. For this reason, a tube-enlarging press according to the prior art has drawbacks, for example, in that when the specifications of a heat exchanger involved are changed, a large amount of time is required for making the arrangements and preparations for rearrangement of fin pressing or supporting jigs as well as for replacement of mandrels in conformity with such change.
The above-mentioned drawbacks will now be explained by the use of FIGS. 1A to 1C and FIG. 2. FIG. 1A is a plan view of a cross fin/tube type heat exchanger, FIG. 1B is a side view thereof, and FIG. 1C is a bottom view thereof. Hereinafter, the construction of and a manufacturing method of the heat exchanger will be described with reference to FIGS. 1A to 1C. The heat exchanger is made by a method of piling a large number of fins 1 and side plates 2 in such a manner that each curl height 8 is increased with respect to the thickness 6 of the pile by the amount which corresponds to a proportion of contraction of a tube 3 due to the enlargement thereof, inserting the tubes into the holes 7 of the fins and the similarly formed holes of the side plates in any optional combination of the tube dispositions, fixing the fins 1 and tubes 3 by way of tube enlargement, and fixing the return pipes 9 by brazing, soldering, etc. It should be noted here that, in FIGS. 1A to 1C, the reference numeral 4 denotes a tube bend portion, the reference numeral 5 the length of the fin, the reference numeral 10 the width of the fin, and the reference numeral 11 the tube arrangement or disposition.
FIG. 2 is a view for explaining the construction of a typical example of the tube-enlarging press for use in a cross fin/tube type heat exchanger. A pressurizing means of this tube-enlarging press has a pressurizing cylinder 14 supported by rectangular frame plates 13 and 13a fixed to an upper part of a frame 12, said pressurizing cylinder 14 being coupled, by a cylinder rod joint 16, to a main pressurizing plate 17 movable under the guidance of support columns 15. A plurality of rod support plates 19 formed with through holes for preventing mandrels 18 from being buckled or bent, pressurizing plate 20, and a fin pressing plate 21 supporting a fin pressing member 22 thereon are arranged such that the two plates 19 and plate 20 are suspended from the main pressurizing plate 17 by means of connecting rods (not shown) so that the former are movable with respect to the latter and the plate 21.
Receivers 24 for supporting the tube bend portions 4 are constructed such that it is possible to prepare the receivers for any optional tube dispositions 11 by reinserting the positioning pins provided on the receivers appropriate ones of the standard through holes provided in a receiver plate 25 in the form of a cross.
Balance cylinders 27 provided on a base 26 are connected to the fin pressing plate 21 to prevent the same from falling. Further, clamp cams 29 retained on cam holders 28 which are movably supported by the support columns 15 are so arranged as to regulate the position of the fin pressing member 22 at which this member 22 reaches for pressing the fins from above when the enlarging of the tubes is completed.
On the other hand, fin keeping members 23a, 23b, 23c and 23d used to keep the four peripheral sides of the fin pile externally are so arranged that they may be rearranged or moved, as required.
However, the above-mentioned prior art tube-enlarging press is designed to be exclusively used for heat exchangers having a fixed size. Therefore, when the area of the fins of a heat exchanger desired to undergo the tube enlargement is changed, a large amount of time is required for newly making the arrangements and preparations for the mandrels 18, fin keeping members 23a to 23d and receivers 24 in conformity with such change.